Linux 2.4.17 bug, mmap of /dev/mem

[David Ashley]

Hmmm. Too many differences, the biggest being 2.4.17 vs 2.4.2.

I forgot to mention to the mailing list that the order of reads/writes to
a page matters.

In every mmap'd page, if the access order is:
reads only    = no problem
writes only   = no problem
write, read, then anything  = no problem
read, write   = trouble

Each page is a separate entity. Meaning if I mmap 2 pages of /dev/mem,
then write to page 0, I'll not have any trouble from page 0 from then on.
But if I read from page 1, then write to page 1, there is a chance of
corrupting linux.

-Dave

>Hi David,
>
>I tested your application on my board (Embedded Planet CLLF (mpc860), Linux
>2.4.2) and made a script that executes it as fast as possible.
>I let it run for 10 minutes on several telnet sessions simultaneously but I
>do not see anything strange... The memory I write to is NVRAM.
>
>Frederic

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